Krishna Bhattarai ^1* Andrew B. Ogden ^2* Sudeep Pandey ² German Sandoya ³ Ainong Shi ⁴ Amol N. Nankar ⁵ Murukarthick Jayakodi ⁶ Alfred (Heqiang) Huo ⁷ Tao Jiang ⁷ Pasquale Tripodi ⁸ Chris Dardick ⁹

• ¹ Department of Horticultural Sciences, Texas A&M AgriLife Research,Texas A and M University, Dallas, United States
• ² Department of Horticulture, University of Georgia, Griffin, United States
• ³ Horticultural Sciences Department, University of Florida, Everglades Research and Education Center. University of Florida – Institute for Food and Agriculture Sciences, Belle Glade, United States
• ⁴ Department of Horticulture, University of Arkansas, Fayetville, United States
• ⁵ Department of Horticulture, University of Georgia, Tifton, United States
• ⁶ Department of Soil and Crop Sciences, Texas A&M University, Texas A&M AgriLife Research and Extension Center, Dallas, United States
• ⁷ Department of Environmental Horticulture, Mid-Florida Research and Education Center, University of Florida, IFAS, Apopka, United States
• ⁸ CREA Research Centre for Vegetable and Ornamental Crops, Pontecagnano-Faiano, Italy
• ⁹ USDA-ARS, Appalachian Fruit Research Station, Kearneysville, United States

Controlled Environment Agriculture (CEA) represents one of the fastest-growing sectors of horticulture. Production in controlled environments ranges from highly controlled indoor environments with 100 percent artificial lighting (vertical farms or plant factories) to high-tech greenhouses with or without supplemental lighting, to simpler greenhouses and high tunnels. Although food production occurs in the soil inside high tunnels, most CEA operations use various hydroponic systems to meet crop irrigation and fertility needs. The expansion of CEA offers promise as a tool for increasing food production in and near urban systems as these systems do not rely on arable agricultural land. In addition, CEA offers resilience to climate instability by growing inside protective structures. Products harvested from CEA systems tend to be of high quality, both internal and external and are sought after by consumers. Currently, CEA producers rely on cultivars bred for production in open-field agriculture. Due to high energy and other production costs in CEA, only a limited number of food crops have proven themselves to be profitable to produce. One factor contributing to this situation may be a lack of optimized cultivars. Indoor growing operations offer opportunities for breeding cultivars that are ideal for these systems. To facilitate breeding these specialized cultivars, a wide range of tools are available for plant breeders to help speed this process and increase its efficiency. This review aims to cover breeding opportunities and needs for a wide range of horticultural crops either already being produced in CEA systems or with potential for CEA production. It also reviews many of the tools available to breeders including genomics-informed breeding, marker-assisted selection, precision breeding, high throughput phenotyping, and potential sources of germplasm suitable for CEA breeding. The availability of published genomes and traitlinked molecular markers should enable rapid progress in the breeding of CEA-specific food crops that will help drive the growth of this industry.